首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   81589篇
  免费   490篇
  国内免费   411篇
化学   26499篇
晶体学   795篇
力学   6868篇
数学   32760篇
物理学   15568篇
  2021年   91篇
  2020年   104篇
  2019年   94篇
  2018年   10481篇
  2017年   10282篇
  2016年   6212篇
  2015年   975篇
  2014年   460篇
  2013年   570篇
  2012年   4058篇
  2011年   10764篇
  2010年   5754篇
  2009年   6202篇
  2008年   6817篇
  2007年   8965篇
  2006年   411篇
  2005年   1485篇
  2004年   1713篇
  2003年   2095篇
  2002年   1096篇
  2001年   287篇
  2000年   324篇
  1999年   185篇
  1998年   228篇
  1997年   175篇
  1996年   241篇
  1995年   137篇
  1994年   102篇
  1993年   107篇
  1992年   85篇
  1991年   82篇
  1990年   72篇
  1989年   79篇
  1988年   79篇
  1987年   76篇
  1986年   73篇
  1985年   80篇
  1984年   68篇
  1983年   63篇
  1982年   71篇
  1981年   54篇
  1980年   64篇
  1979年   57篇
  1978年   54篇
  1914年   45篇
  1913年   40篇
  1912年   41篇
  1909年   41篇
  1908年   40篇
  1907年   33篇
排序方式: 共有10000条查询结果,搜索用时 984 毫秒
1.
Meccanica - In this work we study, from the numerical point of view, a one-dimensional thermoelastic problem where the thermal law is of type III. Quasi-static microvoids are also assumed within...  相似文献   
2.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers.  相似文献   
3.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant.  相似文献   
4.
5.
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser.  相似文献   
6.
The reaction mechanism for the hydrolysis of trimethyl phosphate and of the obtained phosphodiester by the di‐CoII derivative of organophosphate degrading enzyme from Agrobacterium radiobacter P230(OpdA), have been investigated at density functional level of theory in the framework of the cluster model approach. Both mechanisms proceed by a multistep sequence and each catalytic cycle begins with the nucleophilic attack by a metal‐bound hydroxide on the phosphorus atom of the substrate, leading to the cleavage of the phosphate‐ester bond. Four exchange‐correlation functionals were used to derive the potential energy profiles in protein environments. Although the enzyme is confirmed to work better as triesterase, as revealed by the barrier heights in the rate‐limiting steps of the catalytic processes, its promiscuous ability to hydrolyze also the product of the reaction has been confirmed. The important role played by water molecules and some residues in the outer coordination sphere has been elucidated, while the binuclear CoII center accomplishes both structural and catalytic functions. To correctly describe the electronic configuration of the d shell of the metal ions, high‐ and low‐spin arrangement jointly with the occurrence of antiferromagnetic coupling, have been herein considered.  相似文献   
7.
8.
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号